The present invention relates to an electric drive control apparatus and an electric drive control method.
Generally, an electric vehicle, for example an electric automobile, is provided with a drive motor as an electric machine. A hybrid vehicle includes a drive motor and a generator as the first and the second electric machines, respectively. Both the drive motor and the generator are disposed to be rotatable, and each include (1) a rotor with a magnetic pole pair each formed of the permanent magnets of N pole and S pole, respectively, and (2) a stator disposed radially outward of the rotor, with the stator having stator coils at U, V and W phases, respectively.
The electric drive unit is disposed for driving the drive motor in order to generate the drive motor torque or the generator in order to generate the generator torque. The drive motor control unit for driving the drive motor and the generator control unit for driving the generator are disposed as the electric machine control system in order (1) to send pulse width modulation signals at U-phase, V-phase and W-phase generated by the drive motor control unit and the generator control unit to the inverter, and (2) to supply the phase current generated by the inverter, that is, the current at the U-phase, V-phase and W-phase to the stator coil such that the drive motor torque and the generator torque are generated.
Assuming that the direction along the magnetic pole pair of the rotor is defined as a d-axis, and the direction perpendicular to the d-axis is defined as a q-axis, the drive motor control unit executes a feedback control through the vector control calculation on the d-q axis model. The drive motor control unit detects the current applied to each stator coil, the magnetic pole position of the rotor, and a DC voltage at the inlet of the inverter and the like. The drive motor control unit also converts the detected current into the d-axis current and the q-axis current based on the magnetic pole position. Then, the drive motor control unit calculates a d-axis current command value and a q-axis current command value that each represent the target value of the d-axis current and the q-axis current in reference to the current command value map. As such, a d-axis voltage command value and a q-axis voltage command value each represent the target value of the d-axis voltage and the q-axis voltage calculated based on the deviation between the d-axis current and the d-axis current command value, the deviation between the q-axis current and the q-axis current command value, and parameters of the drive motor.
A drive motor target torque that represents the target value of the drive motor torque, and the d-axis current command value and the q-axis current command value in correlation with the DC voltage and the angular velocity are stored in the current command value map. The parameters include a counter-electromotive voltage constant MIf, the winding resistance Ra of each stator coil, and inductances Ld and Lq, which are used for calculation of the interference term so as to suppress the interference between the axes d and q (see, for example, Japanese Patent Application Publication No. JP-A-11-150996).